It is known that, in workshops, machine tools are fixed to the floor by suitable means such as bolts, clamps or otherwise. These arrangements, although satisfactory from the point of view of the fixing in itself, have the major disadvantage of having no effect in reducing the vibration inherent in the operation of the machines. This vibration is transmitted to the surrounding range of machine tools. This causes maladjustment of the other machines and their components.
Moreover, such fixings by bolts or clamps prove unsuitable when the need arises to replace a machine in the minimum of time, in particular because of the inaccessibility of one or more of these fixing elements. In addition, in the case of machines whose weight is relatively great, it is often difficult to position each of the bolts rapidly in the corresponding holes in the support.
According to the device described in published French patent application 2 361 599 and shown in FIG. 1, the bearing parts 1 of the machine to be fixed are placed on a bearing face 2. The bearing face 2 has a plurality of recesses 3 connected to a suction device and provided with an airtight covering 4. The bearing parts of the machine are placed on the bearing face 2 through airtight seals 5 placed around the recesses. The seals 5 are partially embedded in the housings so that the airtight bearing always takes place on these seals. These seals can, by way of example, consist of an elastomer material. These seals, in addition to providing the vacuum-tight function, absorb the vibration due to the operation of the machine 7. As is well known in the art, the characteristics of the seals are adapted according to the weight of the machine. Such a device, although satisfactory from the point of view of the fixing to the floor under the effect of the negative pressure applied in the recesses, has a certain number of disadvantages:
the recesses described in this document are, because of their shape, difficult and expensive to produce; PA1 the suction exerted on the bearing surfaces of the machine is limited to the surfaces defined by the airtight seals, which, for relatively light machines, may prove insufficient; PA1 the positioning of the machine on the seals is not without problems since, particularly in the case of heavy machines, it is often necessary, in order to position the machine precisely, to slide it over the bearing face. There is a risk that such a movement may damage or displace the seals; PA1 finally, as mentioned in the document, the characteristics of the seal, in particular the dimensional characteristics, are calculated according to the load resulting from the weight of the machine, the manufacturers of the elastomer materials making up the seals in fact providing graphs making it possible to calculate accurately, for a given thickness of elastomer material, the area of material required for absorbing the vibration to the greatest possible extent. According to the device described in the patent, the carrying surface is formed by the surface of all the seals distributed over the bearing face 2. Such an arrangement makes it difficult to adapt the carrying surface according to the weight of the machine, particularly when the machine is changed for another one whose weight is not necessarily identical. This involves in particular the replacement of at least some of the seals, and the gain in carrying surface may be limited by the space existing between adjacent seals on the bearing face. PA1 a fixed frame (10); PA1 a bearing structure (13) positioned on the fixed frame (10) and provided for receiving a machine (20), the bearing structure comprising a plurality of holes over substantially the whole of its surface; PA1 means for selectively connecting the holes to a pressure source or a vacuum source (17); characterized in that it comprises means (12) provided for absorbing the vibration generated by the operation of the machine or by its environment, the holes (14) provided in said bearing structure (13) opening into the surface of the bearing (13) directly in contact with the bearing face or parts of the machine so that means (12) for absorbing the vibration can be positioned between the fixed frame (10) and the bearing structure (13).
Published British patent specification No. 1 081 915 describes a combustion engine support comprising a bearing structure positioned on a frame and on which is located a combustion engine, means located between the bearing structure and the frame being provided for absorbing the vibration generated by the operation of the engine. Nowhere in this specification is it suggested to use means for facilitating the positioning of the engine on the bearing structure as well as its holding.
Published French patent application No. 2 207 845 describes a process and a device for moving an apparatus on a fixed frame. No means are disclosed for absorbing the vibration generated by the apparatus during its operation. Furthermore, the apparatus has to be first positioned on a bearing structure, and then, the bearing structure which is mounted on the frame can be easily moved on the frame by means of an air cushion created between the bearing structure and the frame. The problem is that no means are provided for easily positioning the apparatus on the bearing structure which is an important drawback for heavy apparatus.
Swiss patent No. 673 829 describes a process for moving a load on a frame. As in the just mentioned French Application nothing is disclosed for solving the problem of absorbing the vibration, the resilient means (15, FIG. 2) being provided for compensating the surface irregularities of the parts in contact with the bearing structure and the frame so that the bearing force created by air pressure is equally distributed over the whole contact surface between the two elements. In fact, the problem of the vibration had not to be addressed with such an apparatus since its main object is to move a "passive" load which does not generate any vibration. Furthermore nothing is disclosed to immobilize the load on the frame. At least, the load needs to be first totally positioned on the bearing structure without any facilitating means, before benefiting from the facilitating means, provided for moving the bearing structure on the frame.